Septic tanks are typically used at dwellings that are not connected to public sewage facilities. The septic tank is typically located underground and is basically a batch sewage processor. Sewage from the dwelling is sent to the septic tank where it is acted on by microorganisms, where through biochemical reactions the sewage is decomposed. Subsequently, liquid and gaseous effluent is discharged into the surrounding soil. Solids remaining in the tank are periodically cleaned. More information regarding septic tanks can be found in, for example, Woodson, R. Dodge: Builder's Guide to Wells and Septic Systems, McGraw Hill; and Burks, Bennette D. and Mary Margaret Minnis: Onsite Wastewater Treatment Systems, Hogarth House, Ltd. Both of these are incorporated herein by reference to the extent they are not inconsistent with the following explicit teachings.
Prior art septic tanks are often made of concrete, glass fiber reinforced resin materials, or rotationally molded plastic materials. Because of the septic tank size and weight, they are typically transported to the work site by truck, and may require a crane for placing into position.